ISS035-E-036842 (11 May 2013) --- Expedition 35 Flight Engineer Tom Marshburn is captured in a close-up image in the Quest Airlock of the International Space Station prior to a space walk which he shared with Flight Engineer Chris Cassidy (out of frame). The NASA astronauts completed the space walk at 2:14 p.m. EDT May 11 to inspect and replace a pump controller box on the International Space Station's far port truss (P6) leaking ammonia coolant. The pair began the 5-hour, 30-minute space walk at 8:44 a.m.